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<p class="level0"><a name="NAME"></a><h2 class="nroffsh">NAME</h2>
<p class="level0">CURLMOPT_TIMERFUNCTION - set callback to receive timeout values <a name="SYNOPSIS"></a><h2 class="nroffsh">SYNOPSIS</h2>
<p class="level0"><pre class="level0">
&#35;include &lt;curl/curl.h&gt;
&nbsp;
int timer_callback(CURLM *multi,    /* multi handle */
&nbsp;                  long timeout_ms, /* see above */
&nbsp;                  void *userp);    /* private callback pointer */
&nbsp;
CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_TIMERFUNCTION, timer_callback);
</pre>
<a name="DESCRIPTION"></a><h2 class="nroffsh">DESCRIPTION</h2>
<p class="level0">Pass a pointer to your callback function, which should match the prototype shown above. 
<p class="level0">Certain features, such as timeouts and retries, require you to call libcurl even when there is no activity on the file descriptors. 
<p class="level0">Your callback function <span Class="bold">timer_callback</span> should install a non-repeating timer with an interval of <span Class="bold">timeout_ms</span>. Each time that timer fires, call either <span Class="emphasis">curl_multi_socket_action(3)</span> or <span Class="emphasis">curl_multi_perform(3)</span>, depending on which interface you use. 
<p class="level0">A <span Class="bold">timeout_ms</span> value of -1 means you should delete your timer. 
<p class="level0">A <span Class="bold">timeout_ms</span> value of 0 means you should call <span Class="emphasis">curl_multi_socket_action(3)</span> or <span Class="emphasis">curl_multi_perform(3)</span> (once) as soon as possible. 
<p class="level0"><span Class="bold">timer_callback</span> will only be called when the <span Class="bold">timeout_ms</span> changes. 
<p class="level0">The <span Class="bold">userp</span> pointer is set with <a Class="emphasis" href="./CURLMOPT_TIMERDATA.html">CURLMOPT_TIMERDATA</a>. 
<p class="level0">The timer callback should return 0 on success, and -1 on error. This callback can be used instead of, or in addition to, <span Class="emphasis">curl_multi_timeout(3)</span>. <a name="DEFAULT"></a><h2 class="nroffsh">DEFAULT</h2>
<p class="level0">NULL <a name="PROTOCOLS"></a><h2 class="nroffsh">PROTOCOLS</h2>
<p class="level0">All <a name="EXAMPLE"></a><h2 class="nroffsh">EXAMPLE</h2>
<p class="level0"><pre class="level0">
static gboolean timeout_cb(gpointer user_data) {
&nbsp;   if (user_data) {
&nbsp;       g_free(user_data);
&nbsp;       curl_multi_setopt(curl_handle, CURLMOPT_TIMERDATA, NULL);
&nbsp;   }
&nbsp;   int running;
&nbsp;   curl_multi_socket_action(multi, CURL_SOCKET_TIMEOUT, 0, &running);
&nbsp;   return G_SOURCE_REMOVE;
}
&nbsp;
static int timerfunc(CURLM *multi, long timeout_ms, void *userp) {
&nbsp;   guint *id = userp;
&nbsp;
&nbsp;   if (id)
&nbsp;       g_source_remove(*id);
&nbsp;
&nbsp;   // -1 means we should just delete our timer.
&nbsp;   if (timeout_ms == -1) {
&nbsp;       g_free(id);
&nbsp;       id = NULL;
&nbsp;   } else {
&nbsp;       if (!id)
&nbsp;           id = g_new(guint, 1);
&nbsp;       *id = g_timeout_add(timeout_ms, timeout_cb, id);
&nbsp;   }
&nbsp;   curl_multi_setopt(multi, CURLMOPT_TIMERDATA, id);
&nbsp;   return 0;
}
&nbsp;
curl_multi_setopt(multi, CURLMOPT_TIMERFUNCTION, timerfunc);
</pre>

<p class="level0"><a name="AVAILABILITY"></a><h2 class="nroffsh">AVAILABILITY</h2>
<p class="level0">Added in 7.16.0 <a name="RETURN"></a><h2 class="nroffsh">RETURN VALUE</h2>
<p class="level0">Returns CURLM_OK if the option is supported, and CURLM_UNKNOWN_OPTION if not. <a name="SEE"></a><h2 class="nroffsh">SEE ALSO</h2>
<p class="level0"><a Class="manpage" href="./CURLMOPT_TIMERDATA.html">CURLMOPT_TIMERDATA</a>, <a Class="manpage" href="./CURLMOPT_SOCKETFUNCTION.html">CURLMOPT_SOCKETFUNCTION</a><p class="roffit">
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